Cook County prosecutors have subpoenaed a Northwestern University professor to release the grades and off-the-record notes of a group of former journalism students. The undergraduate students were investigating an alleged wrongful conviction as part of Northwestern's Innocence Project. Earlier this week, prosecutors claimed that the students paid witnesses in return for statements that would help free a man convicted for a 1978 murder. The students and their professor deny that allegation. Cook County State's Attorney Anita Alvarez talks more about the case.